Tuesday, September 18, 2007

Hurricane Watch

...Most of the computer models predict that a tropical or subtropical depression will form from 93L once it crosses into the Gulf of Mexico. The path such a storm might take is uncertain. A strong ridge of high pressure is setting up over the eastern half of the U.S., and is expected to remain anchored in place for at least ten days.

This is the type of steering pattern we experienced during the Hurricane Season of 2005, and favors westward-moving storms. However, this steering pattern will be complicated by the presence of the upper-level low pressure system moving southwest over the Gulf of Mexico. This upper-level low will gradually weaken. Depending on the strength and movement of this low, the counterclockwise flow around the low could steer 93L on a northwesterly path towards Louisiana. This is the solution of the latest (12Z) runs of the UKMET, GFS, and GFDL models. The intensity such a storm may reach is also highly uncertain.

The storm is starting off without a warm core, which will hamper intensification. Dry air to the west will also cause it problems. The SHIPS intensity model brings 93L to Category 1 hurricane strength by Saturday, and the GFDL predicts 93L will hit New Orleans as a strong tropical storm Friday night. The NOGAPS model predicts 93L will eventually dissipate over the southwestern Gulf, and the HWRF model does not develop 93L, and takes the disturbance to the central Louisiana coast on Saturday afternoon....